Various types of automatic blood analyzing apparatus capable of analyzing a blood sample in a short period of time have been developed and put into practice. However, collected blood is not analyzed as it is, and is normally used for a variety of analyses after the blood is diluted. In addition, for analyses with high accuracy, it is necessary to sufficiently mix the blood and a diluting solution in order to precisely dilute the blood to a desired concentration. Therefore, it is desired that the automatic blood analyzing apparatus include means for mixing or stirring the blood and the diluting solution. For example, in Patent Literature 1, there is disclosed a liquid mixing container for diluting a blood sample. The liquid mixing container having a roughened inner wall contains a liquid injection port formed in an upper thereof, for feeding a diluting solution, and an air injection port formed in a bottom thereof, for injecting air for stirring a liquid. Further, in Patent Literature 2, there is disclosed a system for diluting and mixing a specimen such as blood by discharging the specimen and a diluting solution into a container, and then repeatedly sucking and discharging the liquid in the container using liquid distribution means. In Patent Literature 3, there is disclosed a cuvette for centrifugal stirring. The cuvette has a reagent accommodation formed in a bottom thereof, and a pocket having a sloped wall, formed in a part of a side wall thereof.